Recuperation of Silver of
Pyrite Materials

Mineral Lixiviation
For a space of 30 days tests of bacterial lixiviation were run with a grinded mineral to net -100; the bacterial lixiviation residues were afterwards submitted to a cyanidation. Concerning the extractions one has to:

For 5 days of bacerial lixiviation, 2% Fe is extracted and the cyanidation of these residues reports 42% of extraction of Ag.;

For 30 days of bacterial lixiviation, 17.5% of Fe is extracted and the cyanidation of these residues reports 50% of extraction of Ag.

The extraction of silver by cyanidation of the mineral without previous bacterial lixiviation is of 9%, a pretty low level (refractary material), giving a high consumption (11 lb/t); while, and this is an interesting aspect in the study of this type of residues, in the measure that time of bacterial lixiviation advances if it is true that the extraction of silver is seen incremented; nonetheless, the consumption of cyanide is seen diminished in a 63%.

Concentration Lixiviation
The bacterial lixiviation was evaluated and subsequent cyanidation of the concentrates of the Plant of Flotation. Tests with material at different granulometry were run.

The extraction of iron is seen incremented in size of finer net; at higher time of lixiviation the extraction of iron is incremented.

As is logic, at a higher extraction of iron, one has a higher extraction of silver, due to the fact that a higher liberation of the the same exists; comparing the cynetic of extraction in all the residues as well as in the original concentrate, the maximum tendency of extraction is at one hour after in which the variation is minimal.